From the broader viewpoint of the types of article restraining and releasing mechanisms which have heretofore been proposed or used with shelf type supports in apparatus for dispensing rollable products, it has long been recognized that some provision must be made, not only for normally restraining and then selectively releasing an end-most product for movement off of the shelf to dispense the same, but also for restraining the remaining products against movement off of the shelf while the end-most product is being dispensed. A variety of mechanisms have been suggested or employed for such purpose, including arrangements involving a pair of solenoid-operated shiftable stop elements spaced from each other along the path of products toward the delivery end of the shelf and appropriately controlled by linkages or separate solenoids, constructions involving rockable delivery cradles or rotatable paddle-wheel assemblies which block the path for the remaining products while delivering an end-most product, swingable gates having associated elements or surfaces for delivering one product while blocking the remainder, etc. Representative typical prior mechanisms of this general class are illustrated by U.S. Pat. Nos. 3,325,049, 3,348,733, 3,498,497, 3,540,562, 3,627,172, 3,627,174, 3,737,070 and 3,795,345. In general, however, although operable for the desired purpose, such prior mechanisms have been characterized from a manufacturing and functional standpoint by factors of undue complexity, multiplicity of components, need to provide unusually configured mechanical parts, complication of electrical control circuitry, and the like, with resultant adverse effects upon fabrication costs, operational reliability, or both. Moreover, such prior mechanisms have generally been characterized from a mechanical standpoint by the employment of shiftable elements which either pivot upon axes transverse to the path of products toward the discharge end of the shelf or are reciprocable in nature, thereby normally requiring the provision of driving components or linkages for controlling the shiftable elements at locations inconveniently adjacent the end of the shelf which is typically near the front of many vending machines.
From the more specific viewpoint of dispensing apparatus of the class illustrated in U.S. Pat. Nos. 3,653,540 and 3,737,071, in which supplies of a plurality of selectable products are respectively stored upon and dispensed from individual, preferably interchangeable, drawer-like assemblies, there has heretofore simply been no really satisfactory means proposed for efficiently storing and reliably dispensing rollable products such as generally cylindrical cans containing foods or the like. Since one of the virtues of such class of machines is their adaptability for handling and offering to the consumer a wide variety of packaged products on a selective basis from a single machine, the previous lack of suitable means for effectively handling cans or similar rollable products in such machines has constituted a serious limitation upon their otherwise versatile product-accommodating nature. The need for means to suitably handle canned products in such class of vending machines has recently become more acute for the purpose of satisfying the demands of consumers who desire to obtain from such a machine canned food products to be heated in a microwave oven or the like for consumption along with snack items of the types heretofore conventionally offered from such machines.